Enhancement of red wine colour by pre-fermentation addition of copigments

The effects of pre-fermentation additions of catechin and caffeic acid to musts were investigated. The cultivar Listan negro, a major red grape grown in the Canary Islands, was used for these studies. The addition of catechin at 120 mg/l resulted in only 10% enhancement in wine colour (AU at 520 nm) after fermentation, while caffeic acid, at the same level, enhanced the wine colour by 60%. These results appear to be the first report of such a significant increase in wine colour achieved by pre-fermentation treatments with natural grape constituents, supporting the view that red wine colour is generally limited by the levels of cofactors for copigmentation rather than by the level of anthocyanins alone. This demonstrates the importance of non-pigment composition in establishing red wine colour and the influence of initial must composition.